public partial class Form1 : Form
     {
         [DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)]
         public static extern int SendMessage(IntPtr hWnd, int msg, int wParam, int lParam);
     }

private void Form1_Load_1(object sender, EventArgs e)
         {
            SendMessage(this.progressBar1.Handle, 0x410, 2, 0);//red
            SendMessage(this.progressBar1.Handle, 0x410, 1, 0);//green
            SendMessage(this.progressBar1.Handle, 0x410, 3, 0);//yellow
            SendMessage(this.progressBar1.Handle, 0x410, 2, 0);//red
         }